Generally, an engine includes a cooling system in order to maintain a temperature of the engine within allowable range when the engine may operate under different conditions. The cooling system is designed to limit overheating of the engine in various operating conditions. The cooling system also provides to improve fuel efficiency by controlling a thermostat valve in order to control coolant flow rates in order to provide necessary cooling capacity according to a machine, the engine and/or environmental conditions. The cooling system also provides to reduce emissions as a temperature of an after-treatment system and an intake manifold associated with the engine may dramatically impact engine emissions, such as Nitrous Oxides (NOx), Carbon Monoxide (CO), and/or Particulate Matter (PM).
However, a traditional thermostat valve may be difficult to control in order to achieve the required cooling capacity. Typically, the thermostat valve is actuated by a change of coolant temperature. When the coolant temperature is reduced below a threshold, the thermostat valve may be closed. In such a situation, the coolant may be circulated through the engine without passing through a radiator. When the coolant temperature increases above the threshold, the thermostat valve may open in order to allow the coolant to pass through the radiator. However, there may be a time lag to change the temperature of the coolant via heat transfer. This may result in reduced performance of the cooling system in machines performing repetitive work cycles.
For example, a work cycle for an excavator may include a dig segment, a lift segment, a swing to truck segment, a dump segment, and a swing to worksite segment. When the excavator performs the dig segment, a required engine power may increase immediately, and a dissipated heat from the engine to the coolant may also increase. However, some time may be required for the coolant temperature to increase to the threshold. When the thermostat valve opens due to the increased coolant temperature, the excavator might be performing another segment of the work cycle, such as the swing to truck segment, the dump segment, and so on. As a result, the required engine power may decrease, but the thermostat valve may remain open to provide maximum cooling capacity until the coolant temperature may drop below the threshold.
When the thermostat valve responds to the reduced temperature by closing itself, the excavator might start performing the dig segment or the lift segment. As a result, the coolant temperature may again increase after the thermostat valve may be closed. In order to address the above concern, multiple engine operating parameters may be considered to electronically control the thermostat valve. However, when one or more electronic components may fail, the thermostat valve may not perform satisfactorily in turn resulting in a reduced performance or complete failure of the cooling system. Hence, there is a need for an improved system and method for controlling the cooling system of the engine.
U.S. Pat. No. 7,347,168 (hereinafter referred as the '168 patent) describes an improved vehicle cooling system. The cooling system has the capability of controlling various thermal components to effectively control heating and cooling of an engine of the vehicle based on instantaneous vehicle and ambient conditions and also based upon predictive conditions. These predictive conditions may include information about the upcoming terrain of the route along which the vehicle may travel. However, the system disclosed in the '168 patent may totally lose control function when one or more electronic components may fail. A more robust system is needed to perform control function when one or more electronic components does/do not operate correctly.